Method of preserving and tawing skins.



PATENT Trice,

URY on someone, or VITRY-sUR-sEIN E, FRANCE.

METHOD OF PRESERVING AND TAW'ING SKlNS.

SPECIFICATION forming part of Letters Patent No. 634,337, dated October 3, 1899.

' Application filed March 24, 1898. Serial No. 675,028. (No specimens.)

To all whom it may concern:

Be it known that I, URY DE GI'iNZBURG, of

52 Boulevard Lamouroux, Vitry-sur-Seine,

ing to their nature and thickness.

Seine Department, in the Republic of France, have invented new Improvements in Methods of Preserving and Tawing Skins, (for which Ihave obtained Letters Patent of France for fifteen years, No. 270,276, dated' September 7, 1897 and I do hereby declare that the following is a full and exact description thereof.

In the method to which the present invention relates the cohesion of the fibers of the hide or skin is destroyed and putrefaction is prevented without the help or the format-ion during the operation of any crystallizable salt, which would have the effect of diminishing the strength of the skin. The result is that skins thus treated contain none of the said crystallizable salts, remain permanently flexible, and lose none of the strength they possessed before being treated, nor has water, whether cold or hot, any action whatever on a skin thus prepared.

This new method makes the skin as firm, as supple, and as elastic as may be required for any purpose for which it may be intended.

The application of my method also makes the skin white, and when the skin has to-be dyed the colors become rapidly and completely fixed on it.

My method of preserving and tawing skins may also be applied to either wet or dry skins, the latter being soaked and restored to the state of hides.

The characteristic operations of the method or process take place after the hide or skin has been previously and suitably cleansed and Worked with lime-Water and then unhaired. The hide or skin after having been subjected in any well-known manner to the above preliminary processes is thoroughly Washed in Water, so as not to retain any of the substances, such as sulfo-hydrate of calcium (GaH S used in unhairing the'same. After this begin the operations which constitute my invention. The skins are then immersed in a bath containing one part of sulfite of aluminium (SO*) Al to ten parts of water, the skins being allowed to remainin the bath from ten to forty minutes, accord- Sulfite of aluminium possesses, among other essential the reduction of the fibers produced by the sulfurous anhydrous gas given off are essentially made use of to cause the sulfate of aluminium to penetrate even into the interior of the hides or skins. The action of the said bath is rendered more vigorous by a small addition of hydrochloric acid intended to facilitate the liberation of the sulfurous acid,

according to the chemical equation:

(SO Al +6HO :3SO +Al Ol+3II O.

The chlorid of aluminium thus liberated impregnates the hide or skin at the same time as the sulfate of aluminium. When removed from the said bath, the skins are allowed to drain forafew moments. They are then immersed in an ammoniacal bath. The ammonia, being a stronger base than alumina, separates the latter from the sulfate and chlorid, which thoroughlyimpregnate the hides or skins, and precipitates the alumina in the form of a gelatinous precipate of hydrated alumina. The skins are taken out after a few moments and left to drain. The ammoniacal liquid added to the water to form the bath is sufficient in quantity to'produce the said precipitate. For this purpose the best proportions are twelve parts (by volume) of water to one part of a saturated ammoniacal solution. Upon the completion of these operations in order to dress the skins I cause them to absorb within fulling-mills a firm paste constituted by the mixture of eight parts of Wheaten flour to one part of glycerin, to which latter is added a small quantity of the precipitate of the ammoniacal bath in order to obtain a sufficiently firm paste. Such paste should be absorbed completely before removing the skins from the tolling-mills and before drying them, if they are intended to be used in a white condition, or before dyeing them, which operation maybe undertaken at oncewithoutfurtherpreparation. The skins are then finished in the usual manner.

Having thus fully described my invention, I claim as new and desire to secure by Letters Patent-- 1. The herein-described method of preparing and tawing skins, which consists in first placing the skins in a bath of aluminium sulfite, thereby causing the evolution of anhydrous sulfurous-aeid gas, and steeping the skins thus treated in an ammoniacal bath, to neutralize the acid set free and to produce a precipitate of hydrated alumina upon the skins.

2. A method for preserving and tawing skins, which consists in first placing the skins in a sullitc-of-aluminium bath, in acidulating the said bath by means of hydrochloric acid in order to facilitate the giving off of anhydrous sulfurous-aeid gas, and in steeping the skins thus treated in an ammoniacal bath, which neutralizes the acid set free and produces a precipitate of hydrated alumina on the fibers of the said skins, substantially as described and specified.

In witness whereof I have hereunto set my hand in presence of two witnesses.

URY DE GUNZBURG.

\Vitnesses:

EUGENE WATCHER, EDWARD P. MAoLEAN. 

